This is disgraceful [0], whatever your opinion on illegal immigration.
[0] deporting non-citizens to 3rd-party countries/prisons
Wherever they go, the U.S. taxpayers are stuck footing the bill for their prison stay, food, medical treatment, etc., but why would it need to be in the United States? They have no claim to stay there.
The disgraceful part is sending illegal immigrants without criminal history to maximum-security prisons, sending asylum seekers to prison, or sending anybody to prisons that torture the inmates.